b 1. Field of the Invention
The present invention relates to an image reading apparatus, a control method thereof, and a recording medium.
2. Description of the Related Art
An image reading apparatus such as a copying machine or a multifunction peripheral prints image data of a document or transmits such data to a designated address by acquiring the image data from a document using a reading device and processing the acquired image data. Some image reading apparatuses are equipped with an automatic document feeder. If a plurality of documents is set on the automatic document feeder, the documents are automatically conveyed to a reading portion of the image reading apparatus one sheet at a time. If an image reading apparatus is not equipped with an automatic document feeder, the user needs to set one document each time on the reading portion, which is extremely inconvenient. Thus, the automatic document feeder is a very useful device.
Some automatic document feeders are equipped with an automatic two-sided document conveying function that allows automatic reading of two sides of a document by one reading device. When the automatic two-sided document conveying method is used, first, the front side of the document is read. Next, the document is reversed and the back side of the document is read. If the document is discharged from the apparatus in this state, a side opposite to the front side of the document is discharged face up compared to the document before the conveyance. Thus, after the back side is read, the document is reversed so that the same side is discharged face up between before and after the reading. Then the document is discharged.
As described above, the automatic two-sided document feeder is useful as it can automatically read both sides of a document and free the user from setting the document in the reading portion of the image reading apparatus each time. However, the reading device is not used efficiently since the reading device remains idle for a long period while the document is being reversed after the reading of the front side is finished and while the document is conveyed after the reading of the back side of the document is finished.
Japanese Patent Application Laid-Open No. 2006-327728 discusses a technique, as described below, for reducing the idle time.
First, the front side of the first document is read. Next, while the first document is temporarily conveyed away from the conveyance path for stand-off to be reversed, the front side of the second document is read. Next, the second document is conveyed away from the conveyance path so that it can be reversed. This stand-off place is different from where the first document has been conveyed. While the second document is conveyed away from the conveyance path, the back side of the first document is read.
Then, in order to reverse the first document again, the first document is further conveyed for stand-off to a place different from where the second document has been conveyed (a third place). In the meantime, the back side of the second document is read. Further, in order to reverse the second document again, the second document is conveyed to the third place. While the second document is conveyed to the third place, the first document is discharged from the apparatus. Finally, the second document is also conveyed from the third place and discharged from the apparatus.
In this manner, in reading two-sided documents, the performance of the reading operation is improved since the reading order of the documents is changed and the second document is read while the first document is reversed.
In the method discussed in Japanese Patent Application Laid-Open No. 2006-327728, the order the images of the documents are read is different from the page order of the documents. After the front side of the first document (first page) is read, the front side of the second document (third page) is read. Then, the back side of the first document (second page) is read and the back side of the second document (fourth page) is read. In order to output the images of the documents, which have been read in such an order, in the correct order, it is necessary to temporarily store the images of the plurality of pages in a storage unit and rearrange them.
Some image reading apparatuses include a function that allows transmission of an image that has been read. There are two types of transmission, memory transmission and direct transmission. In memory transmission, the transmission is started after the storage of the images of the plurality of documents is completed. Indirect transmission, the images are transmitted while they are read. Regarding memory transmission, since the images of a plurality of pages can be stored in the storage unit, the page order can be arranged in the correct order. However, for direct transmission, since the image transmission is started before the storage of the images of a plurality of pages is completed, the images are not transmitted in the correct page order.
The image reading apparatus may only have a small capacity storage unit due to cost reasons. Even if the image reading apparatus has a large capacity storage unit, the available free space of the storage unit maybe small depending on the use status. In the case where the storage capacity is small, the storage unit does not have enough capacity for storing the image data of the plurality of pages which have been read. Thus, the storage unit is unable to temporarily store the image data of the plurality of pages. Accordingly, the pages cannot be rearranged and output in the correct order.